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Ground Mulch and Row Covers


Plastic ground mulches are sometimes used for early cucumbers and summer squash as they improve soil temperatures, help control weeds in the row, conserve water, and stimulate early fruiting and productivity. Plastic mulch increases soil temperatures by 10 °F in spring which promotes rapid seed germination and better transplant establishment. Commonly used plastics are embossed black (cheapest) and newer IRT (infrared-transmitting) films which are more expensive, but are quite cost-effective where soil warming is important.

Plastic mulches are laid by machine before planting. Growers commonly use 3 or 4 feet wide plastic mulches which creates a 2 or 3-foot-wide soil cover. Matching the plastic to the laying machine creates the fewest problems during installation. Mulch should be stretched tightly over the bed and have a good seal at the edges. This ensures that the wind cannot dislodge the plastic and pull it out of the ground. Install the drip tape under the plastic at the same time the mulch is laid down. Usually, the mulch is applied several days before seeding or transplant to allow the soil under the plastic to warm.

Plastic mulch laid by a machine and stretched tightly over a bed before plantingPlastic mulch laid by a machine and stretched tightly over a bed before planting.

Plant and row covers can help protect early plantings from frost or wind damage, and enhance yield and earliness. Hot caps and spun-bonded row covers (aka Reemay) are commonly used. Row covers rest directly on top of plants, but should be weighted down to avoid flapping which causes leaf damage. Remember that row covers need to be opened or removed as plants outgrow the cover, when the plants begin to flower, or when temperatures under the cover regularly exceed 90 °F. When transplanting, plastic mulches can get very hot and this can cause stem damage to transplants if they touch the plastic. Be sure to water immediately after planting or mound some soil around the stem to reduce this problem.

Spun-bonded row covers over transplants (top) Spun-bonded row covers over transplants heat damage to plant stems that were touching the hot plastic mulch (bottom)Heat damage to plant stems that were touching the hot plastic mulch.